TransCanada Corp. officials say workers have shut down much of its Keystone pipeline after an oil leak in South Dakota.The Thursday morning leak was detected by crews and isolated, officials say in a statement. The amount leaked is equivalent to about 210,000 gallons of oil, officials say.The pipeline from Hardisty, Alberta, to Cushing, Oklahoma and Patoka, Illinois is expected to remain shut down as crew investigate, according to the company.This is the largest Keystone oil spill to date in South Dakota, said Brian Walsh, a spokesman for the state's Department of Environment and Natural Resources.There were no initial reports of the oil spill affecting waterways, water systems or wildlife, he said."The safety of the public and environment are our top priorities and we will continue to provide updates as they become available," company reps said.Environmental activist group Greenpeace said the spill shows another section of the pipeline in Nebraska should not be approved."The Nebraska Public Service Commission needs to take a close look at this spill," said Rachel Rye Butler of Greenpeace. "A permit approval allowing Canadian oil company TransCanada to build Keystone XL is a thumbs-up to likely spills in the future."The Keystone Pipeline system stretches more than 2,600 miles from Hardisty east into Manitoba and then down to Texas, according to TransCanada. The pipeline transports crude oil from Canada.The proposed Keystone XL Pipeline, which would stretch from Hardisty down to Steele City, Nebraska, would complete the entire proposed system by cutting through Montana and South Dakota.The Sierra Club has also urged Nebraska regulators to reject the proposed Keystone XL oil pipeline after TransCanada Corp.'s existing Keystone pipeline leaked an estimated 210,000 gallons of oil in South Dakota.Sierra Club Beyond Dirty Fuels campaign director Kelly Martin said Thursday that the only way to protect Nebraska communities is to "to say no to Keystone XL."In March, President Donald Trump's administration officially issued a permit that approved construction of the Keystone XL Pipeline.The approval followed years of intense debate over the pipeline amid hefty opposition from environmental groups, who argued that the pipeline supports the extraction of crude oil from oil sands, which pumps about 17 percent more greenhouse gases than standard crude oil extraction. Environmentalists also opposed the pipeline because it would cut across the Ogallala Aquifer, one of the world's largest underground deposits of fresh water.Native American groups have argued the pipeline would cut across their sovereign lands.The commission will announce its ruling on Monday after spending months evaluating arguments for and against the long-delayed project.CNN and The Associated Press contributed.

AMHERST, S.D. —

TransCanada Corp. officials say workers have shut down much of its Keystone pipeline after an oil leak in South Dakota.

The Thursday morning leak was detected by crews and isolated, officials say in a statement. The amount leaked is equivalent to about 210,000 gallons of oil, officials say.

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The pipeline from Hardisty, Alberta, to Cushing, Oklahoma and Patoka, Illinois is expected to remain shut down as crew investigate, according to the company.

This is the largest Keystone oil spill to date in South Dakota, said Brian Walsh, a spokesman for the state's Department of Environment and Natural Resources.

There were no initial reports of the oil spill affecting waterways, water systems or wildlife, he said.

"The safety of the public and environment are our top priorities and we will continue to provide updates as they become available," company reps said.

Environmental activist group Greenpeace said the spill shows another section of the pipeline in Nebraska should not be approved.

"The Nebraska Public Service Commission needs to take a close look at this spill," said Rachel Rye Butler of Greenpeace. "A permit approval allowing Canadian oil company TransCanada to build Keystone XL is a thumbs-up to likely spills in the future."

The Keystone Pipeline system stretches more than 2,600 miles from Hardisty east into Manitoba and then down to Texas, according to TransCanada. The pipeline transports crude oil from Canada.

The proposed Keystone XL Pipeline, which would stretch from Hardisty down to Steele City, Nebraska, would complete the entire proposed system by cutting through Montana and South Dakota.

The Sierra Club has also urged Nebraska regulators to reject the proposed Keystone XL oil pipeline after TransCanada Corp.'s existing Keystone pipeline leaked an estimated 210,000 gallons of oil in South Dakota.

Sierra Club Beyond Dirty Fuels campaign director Kelly Martin said Thursday that the only way to protect Nebraska communities is to "to say no to Keystone XL."

In March, President Donald Trump's administration officially issued a permit that approved construction of the Keystone XL Pipeline.

The approval followed years of intense debate over the pipeline amid hefty opposition from environmental groups, who argued that the pipeline supports the extraction of crude oil from oil sands, which pumps about 17 percent more greenhouse gases than standard crude oil extraction. Environmentalists also opposed the pipeline because it would cut across the Ogallala Aquifer, one of the world's largest underground deposits of fresh water.

Native American groups have argued the pipeline would cut across their sovereign lands.

The commission will announce its ruling on Monday after spending months evaluating arguments for and against the long-delayed project.